Continuous gravity feed system for feeding additives to a drilling mud system

ABSTRACT

An apparatus and a method is provided for feeding drilling fluid additives into drilling mud. The apparatus may have an additive containment device with a top and a bottom. The bottom of the additive containment device may be connected to an outlet. The other end of the outlet may be connected to a valve. A flow nozzle may be connected to the valve so that the flow rate of the additive from the flow nozzle into the drilling mud is substantially constant.

BACKGROUND

Boreholes are frequently drilled into the Earth's formation to recoverdeposits of hydrocarbons and other desirable materials trapped beneaththe Earth's surface. Traditionally, a well is drilled using a drill bitattached to the lower end of what is known in the art as a drillstring.The drillstring is traditionally a long string of sections of drill pipethat are connected together end-to-end through rotary threaded pipeconnections. The drillstring is rotated by a drilling rig at the surfacethereby rotating the attached drill bit. Drilling fluid, or mud, istypically pumped down through the bore of the drillstring and exitsthrough ports at the drill bit. The drilling fluid acts to bothlubricate and cool the drill bit as well as to carry cuttings back tothe surface. Typically, drilling mud is pumped from the surface to thedrill bit through the bore of the drillstring, and is allowed to returnwith the cuttings through the annulus formed between the drillstring andthe drilled borehole wall. At the surface, the drilling fluid isfiltered to remove the cuttings and is often recycled.

Various difficulties may be encountered during the drilling operation,such as a fluid loss event. Drilling also includes numerous operations,including drilling, running casing, finishing, and many others.Additionally, during the drilling operation, various earth formationsmay result in torque or drag issues at the drill bit. Drilling fluidadditives may be added to the drilling mud to address these specificissues or operations, and may be added over a limited time period.

For example, when a drill bit is experiencing torque or drag issues, itmay be desirable to add spotting beads, a micro-bead used to providelubricity at the drill bit. Addition of spotting beads to the drillingmud may frequently be required for only two or three days at a timeduring the drilling operation. As a result, drilling rigs are typicallynot permanently equipped to add spotting beads to the drilling mud, andthis addition is often performed by simply dumping bags of spottingbeads into the mud system. This feed method may result in periodic andinconsistent lubricity at the drill bit and is labor intensive, both ofwhich are undesirable.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a simplified schematic diagram of a gravity assisted drillingadditive feed system according to embodiments herein.

FIG. 2 is a side view of a gravity assisted drilling additive feedsystem according to embodiments herein.

FIG. 3 is a top view of a gravity assisted drilling additive feed systemaccording to embodiments herein, with a hinged top in an open position.

FIG. 4 is a side view of an outlet assembly useful with a gravityassisted drilling additive feed system according to embodiments herein.

FIG. 5A and FIG. 5B are side views of interchangeable nozzles usefulwith a gravity assisted drilling additive feed system according toembodiments herein, where a flow rate/time resulting from the nozzle isindicated on an exterior of the nozzle.

FIG. 6 is a simplified flow diagram of a process for feeding drillingadditives to a mud system according to embodiments herein.

DETAILED DESCRIPTION

Embodiments disclosed herein relate to a continuous gravity feed systemfor feeding additives to a drilling mud system. More specifically,embodiments disclosed herein relate to a portable additive feed systemthat uses gravity to feed spotting beads to a mud system when neededduring a drilling operation.

FIG. 1 illustrates one embodiment of an additive feed system 10. In theembodiment, the additive feed system 10 may include an additivecontainment device 12 having a top 14, a bottom 16 and side walls 30.The additive containment device 12 may hold additives to be added to adrilling mud. Additionally, the additive containment device 12 may be ofany shape configured to hold the additives while allowing the additivesto flow out the bottom 16. For example, the additive containment device12 may be a cylinder or a rectangular prism. The top 14 may be removedfrom the additive containment device 12. The top 14 may also be hingedlyconnected to the side walls 30 of the additive containment device 12 forease of opening and closing. The top 14 may be opened when addingadditives and closed when additives are not being added. The bottom 16may be shaped to convey the additives to an exit of the additivecontainment device 12. For example, the bottom 16 may be a frustoconicalshape or a frusto-tetrahedral shape.

Three or more legs 32 may be attached to the bottom 16 of the additivecontainment device 12. The legs 32 may be fixed to the bottom 16 or maybe removable. Referring to FIG. 1, the legs 32 may be substantiallystraight. Referring to FIG. 2 and FIG. 3, the legs 32 may flareoutwardly to provide a more stable base.

Referring to FIG. 1, the additive containment device 12 may have a topflanged portion 26 and a bottom flanged portion 28. The top flangedportion 26 may include the top 14 of the additive containment device 12.Opposite the top 14, the top flanged portion 26 may have a flange 26F.The bottom flanged portion 28 may include the bottom 16 of the additivecontainment device 12. Opposite the bottom 16, the bottom flangedportion 28 may have a flange 28F. The top flanged portion 26 may beconnected to the bottom flanged portion 28 at the flange 26F and theflange 28F to form the additive containment device 12. In thisembodiment, the top flanged portion 26 may be connected to the bottomflanged portion 28 during operation of the additive feed system 10.

The additive feed system 10 may have an outlet 18 that has a proximalend and a distal end. The outlet 18 may be tapered so that the distalend is narrower than the proximal end. The proximal end of the outlet 18may be connected to the bottom 16 of the additive containment device 12.The interior of the outlet 18 may be substantially smooth to limit oreliminate the additives from accumulating and impeding the flow ofadditive through the outlet 18. The distal end of the outlet 18 may beconnected to a valve 20. The valve 20 may be any type of valve usefulfor solids flow. For example, the valve 20 may be configured so that itonly has a fully on position and a fully off position with nointermediate positions. In some embodiments, the valve 20 may have noflow restrictions that may result in solids accumulation and potentialfor plugging of the valve or otherwise hindering solids flow when thevalve is open. Such a full bore type valve may be beneficial forconsistency of solids flow, especially with respect to a gravity feedsystem disclosed herein.

A screening member 24 may be disposed within additive containment device12 intermediate the top 14 and the bottom 16. The screening member 24may filter or screen the additives disposed within the containmentdevice 12. The screening member 24 may limit or eliminate oversizedsolids or agglomerates from passing through the tank to the outlet 18,avoiding plugging of the feed system or damage or other issues withdownstream equipment, such as a mud pump. In some embodiments, thescreening member 24 may be fixed. In other embodiments, the screeningmember 24 may be removable. The screening member 24 may be disposedbetween the top flange portion 26 and the bottom flange portion 28. Infurther embodiments, the screening member 24 may be removed when the topflange portion 26 and the bottom flange portion 28 are disconnected.Alternatively, the screening member may be fixed to the top flangeportion 26 coplanar with the flange 26F. Additionally, the screeningmember 24 may be fixed to the bottom flange portion 28 coplanar with theflange 28F

The valve 20 is also connected to a flow nozzle 22 having an outlet end36 and a flow rate. The flow nozzle 22 reduces the additive flow areaand may provide a substantially constant rate of additive flow from theoutlet 18. The flow nozzle 22 may provide a substantially constant rateof flow of a drilling fluid additive from the outlet 18. The flow nozzle22 may have a relatively smooth, tapered, inner surface transitioningfrom the outlet port side of the valve 20 to the inner diameter of theoutlet end 36. As shown in FIG. 4, to respond to changing needs in thedrilling mud system, the flow nozzle 22 may be interchangeable. Duringoperation of the the additive feed system 10, the valve 20 may beclosed, and the flow nozzle 22 with a first flow rate may be changed forthe flow nozzle 22 with a second flow rate.

The additive containment device 12 may have an internal volume in therange from about 5 gallons to about 150 gallons or more, and the desiredvolume may depend upon the type and size of additive and the desiredflow rate of additive through the outlet 18 and the nozzle 22. Theinternal volume of the additive containment device 12 may affect thefrequency that the additive containment device 12 must be refilled. Insome embodiments, the internal volume of the additive containment device12 may be in the range from about 10 to about 50 gallons; in the rangefrom about 20 to 40 gallons in other embodiments, such as about 30gallons. The volume of additives within the additive containment device12 may be visually observed via opening of the top 14, tapping of thesides of the additive containment device 12 to gauge the level, or viaone or more sight glasses (not shown) disposed in the side walls 30.

The additive containment device 12 may be made of a plastic material,resulting in a light weight, portable system. Because water may resultin agglomeration of some additives, use of a plastic body, such aspolypropylene or a vinyl polymer, may result in less moisturecondensation within the additive containment device 12. Additionally,plastic may also result in no static charge accumulation to provide forsafe operation in hazardous environments.

The substantially constant rate of flow of the drilling fluid additiveis provided via an inner diameter of the outlet end 36 of the nozzle 22.The restriction of flow area of the nozzle 22 through which the solidsmay pass results in a relatively constant rate of solids to flow viagravity from the additive containment device 12. For example, forspotting beads, such as ALPINE spotting beads, having an averagediameter in the range from about 70 microns to 1000 microns, a nozzlehaving a 1/4 inch inner diameter may provide for a flow rate of about 43lb/h; a nozzle having a 3/8 inch inner diameter may provide for a flowrate of about 130 lb/h, and a nozzle having a 1/2 inch inner diametermay provide for a flow rate of about 200 lb/h. As shown in FIG. 4, theflow nozzle 22 may be adjustable or interchangeable, such as viathreading, quick connects, or other means known to those skilled in theart. Adjustable or interchangeable nozzles having these and other innerdiameters may thus provide for a desired, consistent, flow rate ofdrilling fluid additive, where an operator may select the appropriatenozzle or flow area to achieve the desired additive composition in thedrilling mud. Interchangeable nozzles, such as illustrated in FIG. 5Aand FIG. 5B, may be marked or otherwise identified to indicate the flowrate of drilling fluid additive through the nozzle or the approximatetime for a (50-lb) bag of additive to dispense, thus providing a meansto achieve a desired concentration of additive in the mud system and anindication of the approximate amount of time required to empty additivecontainment device 12.

Referring now to FIG. 6, a simplified flow diagram of a process forfeeding drilling fluid additives to a mud system according toembodiments herein is illustrated. The above described gravity feedsystems may be used to continuously feed drilling fluid additives, suchas spotting beads, to a drilling fluid or mud system. While such asystem may be permanently located proximate a mud system, it isenvisioned that systems herein may be used intermittently duringdrilling processes, such as during operations or times when spottingbeads or other additives are required.

When needed for the temporary feeding of additives to a mud system, theadditive feed system 10 may be delivered to a drilling site or drillingrig, assembled (if necessary) and located proximate a mud system. Forexample, an “open” mud tank 40 containing a drilling fluid or drillingmud 42 may have a flow conduit 44 feeding a mud pump 46. The drillingmud 42 flows from the mud tank 40 through the conduit 44 and enters thesuction of the mud pump 46. The drilling mud 42 is then discharged to anoutlet conduit 48 and fed downhole through the drill string to the drillbit to provide lubrication and drill cuttings removal. The additive feedsystem 10 may be located over a grating 50 or opening in the flowconduit 44 to allow gravity feed of the additive from the nozzle 22 intothe mud system proximate the suction of the mud pump 46.

Following proper location of the additive feed system 10, a drillingfluid additive may be disposed within the additive containment device12, such as via opening and closing of the top 14. The valve 20 may thenbe opened to initiate flow of the additive through the nozzle 22 intothe the mud system via the grating 50. As needed, additional additivemay be added to additive containment device 12 so as to providecontinuous flow of additive over an extended period of time. Thefrequency of such additions may depend upon the size of the additivecontainment device 12 and the flow rate of the nozzle 22, as describedabove. Should the concentration of the additive need to be adjustedduring use, the valve 20 may be closed and the nozzle 22 changed. A flowconduit, such as a pipe, tube, or hose (not illustrated), may beconnected to the nozzle 22 to guide the flow of additive from the nozzle22 to the mud system feed point, such as the grating 50, minimizingeffects of weather, wind, and other external factors as may be presentat a drilling location or drilling rig.

When the drilling fluid additive is no longer required for drillingoperations, the additive containment device 12 may be cleaned,disassembled, and, if necessary, removed from the drill site or drillingrig.

While described above with respect to an “open” mud system, location andoperation of the additive feed system 10 may be performed in othermanners as appropriate to the respective mud system.

As an example of using the additive system during a drilling operation,the lubricity of the drill bit may be increased using spotting beads,such as when a drill bit is experiencing drag and/or torque issues.Spotting beads may be disposed in the additive containment device 12 andfed to the suction side of the pump 46. The flow rate of spotting beadsinto the drilling fluid may be selected to provide a concentration ofspotting beads in the drilling mud in the range from about 2 to about 15lb/bbl, such as in the range from about 8 to about 10 lb/bbl. Thedrilling beads may then travel through the conduit 48 to the drill bit,where the micron size spherical beads may lubricate the drill bit.

Embodiments herein may supply a consistent, uniform mixture of drillingfluid additives, such as spotting beads, in a drilling mud. The uniformmixture of beads resulting from the consistent feed rate provided bysystems herein, for example, may provide for a consistent, controllablesupply of spotting beads, resulting in a constant improvement inlubricity at the drill bit. In contrast, present methods, such as manualdumping of bags of beads, result in “pill” type flow of spotting beadsor otherwise inconsistent concentrations of beads in the drilling fluid,resulting in inconsistent lubricity at the drill bit. As a result,embodiments herein may eliminate the human factor and significantlyimprove drilling performance, including rate of penetration.Additionally, as compared to manual dumping, feed systems according toembodiments disclosed herein may require less manpower and may preventoversized materials from accidentally being introduced to the system.

Feed systems according to embodiments herein may be relatively small insize, especially compared to the mud tanks (that may be 2000 bbl orlarger in volume), portable, lightweight, and easy to transport,install, and dismantle. Additionally, embodiments herein may provide forinterchangeable nozzles to accurately and predictably control the flowrate of drilling fluid additives. The relatively simple operation of thegravity feed system may thus improve overall operations at a drillingsite or drilling rig and may be extremely beneficial, especially forshort duration needs, such as spotting.

Although only a few example embodiments have been described in detailabove, those skilled in the art will readily appreciate that manymodifications are possible in the example embodiments without materiallydeparting from this invention. Accordingly, all such modifications areintended to be included within the scope of this disclosure as definedin the following claims. In the claims, means-plus-function clauses areintended to cover the structures described herein as performing therecited function and not only structural equivalents, but alsoequivalent structures. Thus, although a nail and a screw may not bestructural equivalents in that a nail employs a cylindrical surface tosecure wooden parts together, whereas a screw employs a helical surface,in the environment of fastening wooden parts, a nail and a screw may beequivalent structures. It is the express intention of the applicant notto invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of theclaims herein, except for those in which the claim expressly uses thewords ‘means for’ together with an associated function.

What is claimed:
 1. An apparatus comprising: an additive containment device having a top and a bottom; an outlet having a proximate end and a distal end wherein the proximate end is connected to the bottom of the additive containment device; a valve connected to the distal end of the outlet; and a flow nozzle connected to the valve wherein the flow rate of the additive from the flow nozzle is substantially constant.
 2. The apparatus of claim 1 further comprising a screening member disposed intermediate the top and the bottom.
 3. The apparatus of claim 1 further comprising at least three legs attached to the bottom of the additive containment device.
 4. The apparatus of claim 1 wherein the top of the additive containment device is removable.
 5. The apparatus of claim 1 wherein the additive containment device comprises a flanged top portion and a flanged bottom portion.
 6. The apparatus of claim 3 wherein the legs are removable.
 7. The apparatus of claim 1 wherein the top of the additive containment device is hingedly connected to the additive containment device.
 8. The apparatus of claim 5 wherein the screening member is disposed within the additive containment device intermediate the flanged top portion and the flanged bottom portion and further wherein the screening member is removable.
 9. The apparatus of claim 5 wherein the flanged bottom portion of the additive containment device is frustoconical.
 10. An apparatus comprising: an additive containment device having a top, a bottom, a top flanged portion and a bottom flanged portion wherein the top portion is removable; a screening member intermediate the top flanged portion and the bottom flanged portion of the additive containment device wherein the screening member is removable; an outlet having a proximate end and a distal end wherein the proximate end is connected to the bottom of the additive containment device; a valve connected to the distal end of the outlet; and a flow nozzle connected to the valve wherein the flow nozzle is interchangeable.
 11. The apparatus of claim 10 further comprising at least three legs connected to the bottom flanged portion of the additive containment device wherein the legs are removable.
 12. The apparatus of claim 10 wherein the top of the additive containment device is hingedly connected to the additive containment device wherein the top has an open position and a closed position.
 13. A method for continuous gravity feed of additives into drilling mud during a drilling operation, the method comprising: selecting a drill fluid additive; feeding the drill fluid additive into drilling mud, wherein the drill fluid additive is fed at a substantially constant flow rate and further wherein the drill fluid additive is fed by gravity; mixing the drill fluid additive into the drilling mud; pumping the mixture of the drill fluid additive and the drilling mud into the wellbore.
 14. The method of claim 13 further comprising assembling an additive feed system after commencing the drilling operation. 